4^(2 - x)·2^(x + 3)/16^x = 1/8
2^(2·(2 - x))·2^(x + 3)/2^(4·x) = 1/2^3
2^(2·(2 - x) + (x + 3))/2^(4·x) = 1/2^3
2^(7 - x)/2^(4·x) = 1/2^3
2^((7 - x) - 4·x) = 2^(-3)
2^(7 - 5·x) = 2^(-3)
7 - 5·x = -3---> x = 2
Portiamo tutto a base 2
2^[2(2-x)]*2^(x+3) * 8 = 16^x
2^(4-2x) * 2^(x+3) * 2^3 = 2^(4x)
4 - 2x + x + 3 + 3 = 4x
- x + 10 = = 4x
4x + x = 10
5x = 10
x = 10/5 = 2